Banks and thrifts reported a total of $3.12 billion in income on their mortgage-banking operations during the fourth quarter of 2017, a 12.6 percent downturn from the previous period, according to an Inside Mortgage Trends analysis of call reports. The final lap of 2017 generated the weakest quarterly profit figure for the industry since the disastrous second quarter of 2011, when banks booked a massive $9.37 billion loss on mortgage banking. Most of that loss ... [Includes one data chart]